This invention relates to a washing machine and, more especially, this invention relates to a washing machine having electronic control means for detecting the quantity and type of laundry in a load of laundry to be washed.
Washing machines are known comprising electronic control means for detecting the quantity and type of laundry in a load to be washed. The ability to detect the quantity and type of the laundry in a load enables the electronic control means to adjust to the detected quantity and type of the laundry in a load, and thereby always provide optimum washing conditions irrespective of the quantity and type of the laundry in the load.
The electronic control means in the known washing machines are all relatively similar because only a relatively small number of properties of the laundry are suitable for detection. Typical of such properties are the water absorbent properties of the laundry and the water release properties of the laundry. Washing machines having generally similar electronic control means are disclosed in DE 4122307, EP 787848 and EP 717139.
In DE 4122307, the electronic control means relies on time intervals following the first two intakes of water, but only considers the differences between the time intervals.
In EP 787848, the electronic control means requires major changes to the initial phase of the washing program, as well as to the duration of the first two water intakes and to the duration of the following agitation periods. The decision parameter is the value of a ratio that is obtained by dividing the time of a third non-preset water intake by the time of a first water intake. An agitation phase follows with a preset duration. After completion of the agitation phase, the time until a lowered water level is restored is measured. The duration of the agitation phase and the water intake are strictly controlled or predetermined.
In EP 717139, the washing machine is fed with information about the quantity of the laundry in the load. The aim is merely to detect the type of the laundry in the load. Also, the washing machine operates with a water circulation installation giving jets of water. The electronic control means looks at the percentage of water being soaked up by the load, after filling a definite amount of water into the drum and subsequently agitating the drum for a certain number of revolutions. Thus the washing machine disclosed in EP 717139 utilises a relatively direct way of detecting the type of laundry in a load.
It is an aim of the present invention to provide a washing machine which enables as compared with the above known washing machines, a more accurate estimate of the quantity and type of the laundry in the load, a shorter washing program duration, and less usage of water.
Accordingly, the present invention provides a washing machine comprising a drum for receiving a load of laundry to be washed, a detergent chamber for receiving detergent to be used in the washing of the laundry, a water intake valve for allowing a water intake into the washing machine, electronic control means, for detecting the quantity and type of the laundry in the load and for providing washing programs for the washing machine, and a pressure sensor which acts to measure pressure signals used for determining the quantity and type of the laundry in the load.
The washing machine of the present invention is such that the electronic control means is able to take into account characteristics of the laundry that depend upon the type and quality of fibre of the laundry, as well as the structure of the fabric of the laundry. In order to achieve this identification, the initial phase of water intake and agitation, until an introduced load is completely wet, is altered in such a way that it supplies sufficient information for the identification of the laundry. The washing machine of the present invention may operate such that the interval between water pressure levels for opening and closing of the water intake valve may be decreased by setting the required pressure for opening the water intake valve to a higher value. This achieves a smaller amount of water per intake, which enables more precise control in the amount of water needed for any one particular load. The washing machine of the present invention may give a very high resolution of detection of the quantity of the laundry in the load in the washing machine.
The washing machine may be one in which the control of the water intake is effected by the pressure sensor measuring the pressure, and in which the measuring of the pressure signals is in dependence upon water absorption and water release properties of the laundry in the load. In this case, the washing machine may be one in which the electronic control means operates to determine the quantity of the laundry in the load by counting the number of openings of the water intake valve and a stabilised pressure value in the pressure signal measured by the pressure sensor, and in which the electronic control means operates to determine the type of the laundry in the load by utilising (i) the time interval between a second opening of the water intake valve and a first closing of the water intake valve, and the time interval between a third opening of the water intake valve and a second closing of the water intake valve, (ii) the time values of the first closing of the water intake valve, the second closing of the water intake valve, the second opening of the water intake valve, and the third opening of the water intake valve, and (iii) the water release properties of the laundry in the load as indicated by pressure changes measured by the pressure sensor.
The washing machine may be one in which the electronic control means determines the quantity of the laundry in the load by counting the number of openings of the water intake valve at a plurality of different first decision levels.
Preferably, there are six of the different first decision levels.
Preferably, the six different first decision levels are an almost empty level, a very low volume level, a low volume level, a medium volume level, a high volume level, and a very high volume level.
The washing machine may be one in which the electronic control means determines the type of laundry in the load by utilising (i) the time interval between a second opening of the water intake valve and a first closing of the water intake valve, and the time interval between a third opening of the water intake valve and a second closing of the water intake valve, (ii) the time values of the first closing of the water intake valve, the second closing of the water intake valve, the second opening of the water intake valve, and the third opening of the water intake valve, and (iii) the water release properties of the laundry in the load as indicated by pressure changes measured by the pressure sensor, at a plurality of different second decision levels.
Preferably, there are three of the different second decision levels.
Preferably, the three different second decision levels are for the laundry being such that it has high water absorption and respective water release properties, for the laundry being such that it has medium water absorption and respective water release properties, and for the laundry being such that it has low water absorption and respective water release properties. Examples of laundry having high water absorption and respective water release properties are cotton terry towels and knitted wool articles. Examples of laundry having medium water absorption and respective water release properties are standard cotton articles. Examples of laundry having low water absorption and respective water release properties are synthetic fabrics and jeans.
In a first embodiment of the invention, the washing machine is one in which the electronic control means controls the water intake by the following steps:
(i) opening the water intake valve until a predetermined upper threshold pressure value which is measured by the pressure sensor is reached;
(ii) closing the water intake valve, commencing agitation, and allowing the laundry to absorb water until a predetermined lower threshold pressure value is reached;
(iii) repeating steps (i) and (ii) until the laundry is completely wet, and the measured pressure stabilises at a level; and
(iv) providing a period during which there is no agitation of the laundry and no intake of the water, whereby the laundry releases water and causes a pressure increase, and the pressure sensor measures the pressure increase to obtain information about the type of the laundry in the load.
In a second embodiment of the invention, the washing machine is one in which the electronic control means controls the water intake by the following steps:
(i) opening the water intake valve until a predetermined upper threshold pressure value which is measured by the pressure sensor is reached;
(ii) closing the water intake valve, commencing agitation, and allowing the laundry to absorb water until a predetermined lower threshold pressure value is reached;
(iii) repeating steps (i) and (ii) for a predetermined duration unless the lower threshold pressure value is reached;
(iv) closing the water intake valve, commencing agitation, and maintaining the agitation for a predetermined period even if the pressure level drops below the predetermined minimum lower threshold value;
(v) at the end of the predetermined period in step (iv) opening the water intake valve if the pressure level in step (iv) has dropped below the predetermined minimum lower threshold value;
(vi) repeating steps (iv) and (v) until the laundry is completely soaked as indicated by a stabilisation of the pressure;
(vii) checking after a predetermined time that the pressure is still stable and if the pressure has dropped repeating step (v) one more time; and
(viii) providing a period during which there is no agitation and no intake of the water, whereby the laundry releases water and causes a pressure increase, and the pressure sensor measures the pressure increase to obtain information about the type of the laundry in the load.
In the first and the second embodiments of the invention, the washing machine may be such that the electronic control means determines the quantity of the laundry in the load by utilising the number of openings of the water intake valve and the mean of the pressure value where the measured pressure signal is stabilised. Also, the washing machine may be such that the electronic control means determines the type of the laundry in the load by utilising the timing of the openings and closings of the water intake valve and the water release properties of the laundry in the load.